HELP!!! 5.4 accelerates rough
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Joined: Oct 2002
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From: carlsbad
HELP!!! 5.4 accelerates rough
I have a 1997 F150 with the 5.4 Liter engine, 118000 miles, and recent development of a knocking sound at all engine speeds.
I changed the fuel and air filters, pulled and changed the spark plugs, checked cylinder compression with all cylinders indicating between 150 and 160 psig, checked all injector resistance, checked all injector circuits for proper signal, checked all coils (changed one dead coil), cleaned the fuel injectors using BG cleaner, installed new catalytic converters and duel exhaust due to a suspected restriction in one of the converters.
The results have been good except that the engine still hesitates and misses during cold throttle up. It is more severe during hard acceleration. It improves significantly after the engine has warmed up. The knocking sound has been eliminated.
Any ideas of other items I should check? Could it still be a fouled injector?
I changed the fuel and air filters, pulled and changed the spark plugs, checked cylinder compression with all cylinders indicating between 150 and 160 psig, checked all injector resistance, checked all injector circuits for proper signal, checked all coils (changed one dead coil), cleaned the fuel injectors using BG cleaner, installed new catalytic converters and duel exhaust due to a suspected restriction in one of the converters.
The results have been good except that the engine still hesitates and misses during cold throttle up. It is more severe during hard acceleration. It improves significantly after the engine has warmed up. The knocking sound has been eliminated.
Any ideas of other items I should check? Could it still be a fouled injector?
Postmaster
Joined: May 2002
Posts: 3,028
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From: Annapolis, Maryland
HELP!!! 5.4 accelerates rough
You could also try resetting the computer - disconnect the battery for a half hour and see if that may solve it. Maybe the computer isn't compensating for the cold so it's sputtering (like my 77 MGB is right now)
Also, a clogged injector may be something to look at. Have you tried those over the counter injector cleaners? If you dump 2 of those in their with a tank of premium, it should clean it up to some extent.
I doubt you want to replace all of the injectors, but I can't think of anything else.
I'm sure your dealer will gladly charge you $80 to take a peek (don't forget the $35 in "shop supplies
") and give you their explanation.
Either way, good luck!
XXL
Also, a clogged injector may be something to look at. Have you tried those over the counter injector cleaners? If you dump 2 of those in their with a tank of premium, it should clean it up to some extent.
I doubt you want to replace all of the injectors, but I can't think of anything else.
I'm sure your dealer will gladly charge you $80 to take a peek (don't forget the $35 in "shop supplies
") and give you their explanation. Either way, good luck!
XXL
Post Fiend
Joined: Jan 2002
Posts: 5,859
Likes: 7
From: USA
HELP!!! 5.4 accelerates rough
By any chance did you put a fuel pressure tester guage on the fuel rail ? ,to see if the fuel pressure is where it should be.
the fuel pump has a chk valve built into it.they have been known to leak by and cause fuel pressure problems.
all sparkplugs looked the same color after removing them?
Rich
the fuel pump has a chk valve built into it.they have been known to leak by and cause fuel pressure problems.
all sparkplugs looked the same color after removing them?
Rich
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